Strengthening and baking method for fan casting sand mold

Abstract

The invention discloses a fan casting sand mold strengthening and baking method, and relates to the technical field of fan casting, the fan casting sand mold strengthening and baking method comprises the following steps: S1, sand mold preparation: mixing sand, resin and a curing agent according to a mass ratio of 1: 0.01: 0.005, and carrying out natural reaction molding to obtain a sand mold matrix; s2, coating preparation: mixing the high-temperature-resistant fireproof coating with industrial alcohol to prepare slurry suitable for flow coating; s3, surface flow coating is conducted, specifically, the surface of the sand mold base body is coated with the slurry in a flow mode, and a uniform coating is formed; and S4, ignition and spontaneous combustion: igniting the slurry on the surface of the sand mold after flow coating. According to the method, through a synergistic dehydration mechanism combining ignition spontaneous combustion and staged baking, most of surface and shallow solvents are rapidly removed through alcohol spontaneous combustion, deep bound water is thoroughly and stably removed through a mild baking strategy of low temperature and high temperature, it is ensured that the sand mold is in an absolute dry state before pouring, and the quality of the sand mold is guaranteed. Therefore, the explosion risk caused by instant expansion of water vapor is eradicated.

Description

Technical Field

[0001] This invention relates to the field of wind turbine casting technology, specifically a method for strengthening and baking a sand mold for wind turbine casting. Background Technology

[0002] In the casting production process of wind turbine components, the preparation and treatment of sand molds are crucial steps affecting casting quality and production safety. Currently, resin sand technology is commonly used to make sand molds, and refractory coatings are applied to their surfaces to improve surface quality and resistance to molten iron erosion.

[0003] Traditional sand mold baking processes rely primarily on prolonged heating and drying using kiln drying or hot air convection to remove coating solvents and moisture. However, this single hot baking method has significant drawbacks: First, if baking is insufficient, residual solvents or moisture deep within the sand mold will vaporize instantly upon contact with molten iron, generating immense pressure and causing the sand mold to crack, leading to safety and quality incidents. Second, simple hot air drying is insufficient to effectively strengthen the coating surface; the sand mold surface lacks hardness and roughness, making it prone to defects such as sand erosion and adhesion during casting, affecting casting accuracy. Furthermore, the entire process relies on an external heat source, resulting in high energy consumption, long production cycles, and low efficiency.

[0004] Although the industry has tried to improve the above problems by adjusting the coating formula or extending the baking time, it has never been able to fundamentally overcome the technical limitations of single heat energy drive and dehydration and enhanced separation. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for strengthening and baking sand molds for wind turbine casting.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A method for strengthening and baking a sand mold for wind turbine casting, comprising the following steps:

[0007] S1. Sand mold preparation: Sand, resin and curing agent are mixed in a mass ratio of 1:0.01:0.005 and allowed to react naturally to form the sand mold matrix;

[0008] S2. Coating preparation: Mix the high-temperature resistant refractory coating with industrial alcohol to prepare a slurry suitable for flow coating;

[0009] S3. Surface coating: The slurry is applied to the surface of the sand mold substrate to form a uniform coating.

[0010] S4. Ignition and self-ignition: Ignite the slurry on the surface of the sand mold after the coating has been applied, and use the self-ignition of industrial alcohol to initially cure and dry the coating;

[0011] S5. Staged baking: The sand mold, after being ignited and self-ignited, is sent into the baking equipment and subjected to low-temperature baking and high-temperature curing in sequence.

[0012] Preferably, in step S2, the mass ratio of the high-temperature resistant fire-resistant coating to industrial alcohol is 1:0.4.

[0013] Preferably, in step S2, the high-temperature resistant refractory coating is ISOPENG-1600 anti-sulfurization coating, and its working Baume degree is adjusted to 20-50 Bé by adding the industrial alcohol.

[0014] Preferably, the density of the ISOPENG-1600 anti-sulfurization coating is 1.4-1.7 g / cm³. 3 Its main components, by mass percentage, include: 22% carbon, 28% magnesium oxide, and 15% silicon.

[0015] Preferably, in step S4, the duration of ignition and spontaneous combustion is 1 to 3 minutes.

[0016] Preferably, in step S5, the specific parameters for the staged baking are:

[0017] The low-temperature baking temperature is 80℃-120℃, and the baking time is 30-60 minutes;

[0018] The high-temperature curing temperature is 180℃-220℃, and the baking time is 60-120 minutes.

[0019] Preferably, during the low-temperature baking stage, the heating rate from room temperature to the target temperature is controlled to be less than 20°C / hour.

[0020] Preferably, after the high-temperature curing stage is completed, the sand mold is cooled to below 80°C in the baking equipment before being removed from the oven.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. This invention utilizes a synergistic dehydration mechanism combining ignition and self-ignition with staged baking. First, alcohol self-ignition is used to quickly remove most of the surface and shallow solvents. Then, a gentle baking strategy of low temperature followed by high temperature is used to thoroughly and steadily remove deep bound water, ensuring that the sand mold is in an absolutely dry state before casting, thereby eliminating the risk of cracking caused by the instantaneous expansion of water vapor.

[0023] 2. This invention utilizes the instantaneous high temperature of ignition and self-ignition to generate a micro-sintering effect on the coating surface, forming a dense and hard shell that directly improves surface roughness and wear resistance. Simultaneously, the optimized viscosity coating can deeply penetrate the sand mold substrate, forming a robust "mechanical anchoring" structure after curing. This creates a performance gradient transition layer from the substrate to the coating, resulting in high overall strength, effectively preventing sand erosion and adhesion, and ensuring the dimensional accuracy and surface quality of the casting.

[0024] 3. This invention creatively utilizes the chemical energy of alcohol in the coating to complete the initial drying and curing, which greatly reduces the heat load and time required for subsequent baking, shortens the production cycle, reduces energy consumption, and achieves an organic unity of safety, quality and efficiency. Attached Figure Description

[0025] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings, the same reference numerals are used to refer to the same parts. Wherein:

[0026] Figure 1 This is a process flow diagram of the sand mold strengthening and baking method for wind turbine casting described in this invention. Detailed Implementation

[0027] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0028] Example

[0029] like Figure 1 As shown, a method for strengthening and baking a sand mold for wind turbine casting includes the following steps:

[0030] S1. Sand mold preparation: Mix sand, resin and curing agent in a mass ratio of 1:0.01:0.005, and allow them to react naturally to form the sand mold matrix.

[0031] S2. Coating preparation: Mix the high-temperature resistant refractory coating with industrial alcohol to prepare a slurry suitable for flow coating;

[0032] In step S2, the mass ratio of the high-temperature resistant refractory coating to industrial alcohol is 1:0.4;

[0033] In step S2, the high-temperature resistant fire-resistant coating is ISOPENG-1600 anti-sulfurization coating, and its working Baume degree is adjusted to 20-50 Bé by adding industrial alcohol.

[0034] The density of ISOPENG-1600 anti-sulfurization coating is 1.4-1.7 g / cm³. 3 Its main components, by mass percentage, include: 22% carbon, 28% magnesium oxide, and 15% silicon.

[0035] S3. Surface coating: The slurry is applied to the surface of the sand mold substrate to form a uniform coating.

[0036] S4. Ignition and self-ignition: Ignite the slurry on the surface of the sand mold after the coating has been applied, and use the self-ignition of industrial alcohol to perform preliminary curing and drying of the coating;

[0037] In step S4, the ignition and self-ignition time is 1 to 3 minutes.

[0038] S5. Staged baking: The sand mold, after being ignited and self-ignited, is sent into the baking equipment and subjected to low-temperature baking and high-temperature curing in sequence;

[0039] In step S5, the specific parameters for staged baking are as follows:

[0040] The low-temperature baking temperature is 80℃-120℃, and the baking time is 30-60 minutes;

[0041] The high-temperature curing temperature is 180℃-220℃, and the baking time is 60-120 minutes.

[0042] During the low-temperature baking stage, the heating rate from room temperature to the target temperature is controlled within 20℃ / hour.

[0043] The first layer, the macroscopic process framework, replaces pure thermal energy-driven drying with chemical energy-driven drying, changing the traditional single mode that relies on external heat sources for drying from start to finish, and introducing internal chemical energy as the initial driving force. The traditional mode is external heat energy - penetration, evaporation of moisture - drying and curing, while the mode of this invention consists of (chemical energy - instant curing + preliminary drying) + (external heat energy - deep curing + final drying).

[0044] Working Principle: Utilizing chemical energy, in steps S2 and S4, the coating is mixed with flammable industrial alcohol and ignited. The alcohol combustion (rapid oxidation reaction) instantly releases a large amount of heat, a highly efficient internal heat source provided by the material itself. Functional separation is another step, specifically designed to treat the surface and shallow layers of the coating for solvents and moisture. The intensity of the open flame ensures high efficiency and speed (only 1-3 minutes) of the removal process. This stage completes approximately 70%-80% of the solvent removal, significantly reducing the heat load of subsequent traditional baking processes and laying the foundation for energy saving and high efficiency throughout the entire process.

[0045] The second layer, microstructure and interface reinforcement, constructs a gradient transition layer, which explains why this method can simultaneously improve roughness and strength. The key lies in the creation of a high-performance gradient transition layer between the sand mold body and the refractory coating through a unique process.

[0046] Working Principle: The instantaneous high-temperature sintering effect, with the flame temperature of the alcohol ignition (S4) far exceeding the subsequent baking temperature, causes micro-melting of the coating particles (especially the low-melting-point components). The molten particles reconnect and sinter under surface tension, forming a denser and harder sintered shell on the outermost layer of the coating. This directly improves surface roughness (providing ideal adhesion points for molten iron) and wear resistance. Optimized penetration and anchoring: The precisely controlled coating viscosity (Baumé 20-50 Bé) in step S2 ensures excellent flowability and penetration of the slurry. During flow coating (S3), the slurry fully penetrates the pores of the sand mold substrate surface. Subsequently, the alcohol ignition and baking solidify the penetrated coating, acting like countless micro-nails, mechanically anchoring the coating to the sand mold substrate, greatly enhancing coating adhesion and preventing peeling. The entire process creates an ideal gradient structure: a composite layer consisting of a mold substrate, a coating layer that penetrates and cures, and a dense, micro-sintered surface layer. This structure ensures a smooth transition in mechanical and thermal properties between the flexible sand mold and the hard coating, preventing cracking under thermal stress due to abrupt changes in performance.

[0047] The third layer, thermal management and stress control, achieves gentle yet thorough deep processing, which is the deepest principle ensuring the stability and safety of the final quality. It focuses on how to avoid introducing new internal damage when deep processing materials.

[0048] Working Principle: To prevent steam explosions and internal stress, the staged baking in step S5, especially the low-temperature stage (80-120℃) and the controlled heating rate (≤20℃ / hour), is the essence of thermal energy management. Its purpose is to gently remove residual bound water from the sand mold and deep layers of the coating. If the temperature rises too quickly, the deep moisture will vaporize rapidly, and the steam pressure will have nowhere to release, accumulating internally. This can lead to micro-cracks that weaken strength, or even directly cause coating blistering or sand mold cracking—a prelude to the risk of encountering moisture during casting. This process, through slow heating, allows sufficient time for water vapor to diffuse smoothly, releasing internal stress. Deep cross-linking and curing are achieved, and the subsequent high-temperature stage (180-220℃) provides the necessary energy for the resin binder and coating components to complete a deep thermal cross-linking reaction and sintering. This not only further removes the last remaining volatiles but also optimizes the overall strength, thermal stability, and refractoriness of the sand mold and coating.

[0049] After the high-temperature curing stage, the sand mold is cooled to below 80°C in the baking equipment before being removed from the oven. This final cooling process to below 80°C is also crucial for stress control. It avoids rapid cooling stress caused by excessively high oven temperatures, ensuring the stability of the sand mold in terms of dimensions and strength.

[0050] The technical effect of this invention stems from the synergistic effect of the above three levels of principles:

[0051] The chemical energy drive of the first layer provides energy for the instantaneous sintering of the second layer and significantly reduces the thermal load on the third layer;

[0052] The high strength and good adhesion provided by the gradient structure of the second layer enable the sand mold to withstand the thermal and mechanical shocks brought about by the deep baking of the third layer and the final pouring of molten iron.

[0053] The third layer of thermal management consolidates and deepens the achievements of the first two stages, ensuring the integrity and reliability of the final product's internal structure and fundamentally solving the core hidden danger of sand mold cracking.

[0054] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. A method for strengthening and baking a sand mold for casting a wind turbine, characterized in that, Includes the following steps: S1. Sand mold preparation: Sand, resin and curing agent are mixed in a mass ratio of 1:0.01:0.005 and allowed to react naturally to form the sand mold matrix; S2. Coating preparation: Mix the high-temperature resistant refractory coating with industrial alcohol to prepare a slurry suitable for flow coating; S3. Surface coating: The slurry is applied to the surface of the sand mold substrate to form a uniform coating. S4. Ignition and self-ignition: Ignite the slurry on the surface of the sand mold after the coating has been applied, and use the self-ignition of industrial alcohol to initially cure and dry the coating; S5. Staged baking: The sand mold, after being ignited and self-ignited, is sent into the baking equipment and subjected to low-temperature baking and high-temperature curing in sequence.

2. The method for strengthening and baking a sand mold for casting a wind turbine according to claim 1, characterized in that, In step S2, the mass ratio of the high-temperature resistant fire-resistant coating to industrial alcohol is 1:0.

4.

3. The method for strengthening and baking a sand mold for casting a fan according to claim 2, characterized in that, In step S2, the high-temperature resistant refractory coating is ISOPENG-1600 anti-sulfurization coating, and its working Baume degree is adjusted to 20-50 Bé by adding the industrial alcohol.

4. The method for strengthening and baking a sand mold for casting a fan according to claim 3, characterized in that, The ISOPENG-1600 anti-sulfurization coating has a density of 1.4-1.7 g / cm³, and its main components, by mass percentage, include: 22% carbon, 28% magnesium oxide, and 15% silicon.

5. The method for strengthening and baking a sand mold for casting a wind turbine according to claim 1, characterized in that, In step S4, the duration of ignition and spontaneous combustion is 1 to 3 minutes.

6. The method for strengthening and baking a sand mold for casting a wind turbine according to claim 1, characterized in that, In step S5, the specific parameters for the staged baking are as follows: The low-temperature baking temperature is 80℃-120℃, and the baking time is 30-60 minutes; The high-temperature curing temperature is 180℃-220℃, and the baking time is 60-120 minutes.

7. The method for strengthening and baking a sand mold for casting a wind turbine according to claim 6, characterized in that, During the low-temperature baking stage, the heating rate from room temperature to the target temperature is controlled to be less than 20°C / hour.

8. The method for strengthening and baking a sand mold for casting a wind turbine according to claim 6, characterized in that, After the high-temperature curing stage is completed, the sand mold is cooled to below 80°C in the baking equipment before being removed from the oven.

Images